Merge branch 'develop' into copy-free-balance-lookup

This PR refactors `ProcessExecutionPayload` with `ApplyExecutionPayload`
so caller can use Apply method to calculate post state root. Note that
validations are not required for Apply function. We really need the
state mutation lines that's:
```
1. Ensure latest_block_header.state_root is set (if zero, set it to the pre‑payload HashTreeRoot)...
2. processExecutionRequests()
3. QueueBuilderPayment()
4. SetExecutionPayloadAvailability(state.Slot(), true)
5. SetLatestBlockHash(payload.BlockHash())
```
I decided to keep them there because a. it's cheap b. it makes refactor
cleaner to reason c. API/caller may want to validate envelope and bid
consistency (ex: beacon api has option to validate consensus)

beacon-chain/core/gloas/payload.go

@@ -112,6 +112,34 @@ func ProcessExecutionPayload(
 		return errors.Wrap(err, "signature verification failed")
 	}
 
+	envelope, err := signedEnvelope.Envelope()
+	if err != nil {
+		return errors.Wrap(err, "could not get envelope from signed envelope")
+	}
+
+	if err := ApplyExecutionPayload(ctx, st, envelope); err != nil {
+		return err
+	}
+
+	r, err := st.HashTreeRoot(ctx)
+	if err != nil {
+		return errors.Wrap(err, "could not get hash tree root")
+	}
+	if r != envelope.StateRoot() {
+		return fmt.Errorf("state root mismatch: expected %#x, got %#x", envelope.StateRoot(), r)
+	}
+
+	return nil
+}
+
+// ApplyExecutionPayload applies the execution payload envelope to the state and performs the same
+// consistency checks as the full processing path. This keeps the post-payload state root computation
+// on a shared code path, even though some bid/payload checks are not strictly required for the root itself.
+func ApplyExecutionPayload(
+	ctx context.Context,
+	st state.BeaconState,
+	envelope interfaces.ROExecutionPayloadEnvelope,
+) error {
 	latestHeader := st.LatestBlockHeader()
 	if len(latestHeader.StateRoot) == 0 || bytes.Equal(latestHeader.StateRoot, make([]byte, 32)) {
 		previousStateRoot, err := st.HashTreeRoot(ctx)
@@ -128,10 +156,6 @@ func ProcessExecutionPayload(
 	if err != nil {
 		return errors.Wrap(err, "could not compute block header root")
 	}
-	envelope, err := signedEnvelope.Envelope()
-	if err != nil {
-		return errors.Wrap(err, "could not get envelope from signed envelope")
-	}
 
 	beaconBlockRoot := envelope.BeaconBlockRoot()
 	if !bytes.Equal(beaconBlockRoot[:], blockHeaderRoot[:]) {
@@ -217,14 +241,6 @@ func ProcessExecutionPayload(
 		return errors.Wrap(err, "could not set latest block hash")
 	}
 
-	r, err := st.HashTreeRoot(ctx)
-	if err != nil {
-		return errors.Wrap(err, "could not get hash tree root")
-	}
-	if r != envelope.StateRoot() {
-		return fmt.Errorf("state root mismatch: expected %#x, got %#x", envelope.StateRoot(), r)
-	}
-
 	return nil
 }
 

beacon-chain/core/peerdas/validator.go

@@ -73,23 +73,22 @@ func PopulateFromSidecar(sidecar blocks.VerifiedRODataColumn) *SidecarReconstruc
 
 // ValidatorsCustodyRequirement returns the number of custody groups regarding the validator indices attached to the beacon node.
 // https://github.com/ethereum/consensus-specs/blob/master/specs/fulu/validator.md#validator-custody
-func ValidatorsCustodyRequirement(state beaconState.ReadOnlyBeaconState, validatorsIndex map[primitives.ValidatorIndex]bool) (uint64, error) {
-	totalNodeBalance := uint64(0)
+func ValidatorsCustodyRequirement(st beaconState.ReadOnlyBalances, validatorsIndex map[primitives.ValidatorIndex]bool) (uint64, error) {
+	cfg := params.BeaconConfig()
+	idxs := make([]primitives.ValidatorIndex, 0, len(validatorsIndex))
 	for index := range validatorsIndex {
-		validator, err := state.ValidatorAtIndexReadOnly(index)
-		if err != nil {
-			return 0, errors.Wrapf(err, "validator at index %v", index)
-		}
-
-		totalNodeBalance += validator.EffectiveBalance()
+		idxs = append(idxs, index)
+	}
+	totalBalance, err := st.EffectiveBalanceSum(idxs)
+	if err != nil {
+		return 0, errors.Wrap(err, "effective balances")
 	}
 
-	cfg := params.BeaconConfig()
 	numberOfCustodyGroups := cfg.NumberOfCustodyGroups
 	validatorCustodyRequirement := cfg.ValidatorCustodyRequirement
 	balancePerAdditionalCustodyGroup := cfg.BalancePerAdditionalCustodyGroup
 
-	count := totalNodeBalance / balancePerAdditionalCustodyGroup
+	count := totalBalance / balancePerAdditionalCustodyGroup
 	return min(max(count, validatorCustodyRequirement), numberOfCustodyGroups), nil
 }
 

beacon-chain/state/interfaces.go

@@ -152,6 +152,7 @@ type ReadOnlyBalances interface {
 	Balances() []uint64
 	BalanceAtIndex(idx primitives.ValidatorIndex) (uint64, error)
 	BalancesLength() int
+	EffectiveBalanceSum([]primitives.ValidatorIndex) (uint64, error)
 }
 
 // ReadOnlyCheckpoint defines a struct which only has read access to checkpoint methods.

beacon-chain/state/state-native/getters_validator.go

@@ -8,6 +8,7 @@ import (
 	"github.com/OffchainLabs/prysm/v7/encoding/bytesutil"
 	ethpb "github.com/OffchainLabs/prysm/v7/proto/prysm/v1alpha1"
 	"github.com/OffchainLabs/prysm/v7/runtime/version"
+	"github.com/pkg/errors"
 )
 
 // Validators participating in consensus on the beacon chain.
@@ -80,6 +81,25 @@ func (b *BeaconState) ValidatorAtIndex(idx primitives.ValidatorIndex) (*ethpb.Va
 	return b.validatorAtIndex(idx)
 }
 
+// EffectiveBalances returns the sum of the effective balances of the given list of validator indices, the eb of each given validator, or an
+// error if one of the indices is out of bounds, or the state wasn't correctly initialized.
+func (b *BeaconState) EffectiveBalanceSum(idxs []primitives.ValidatorIndex) (uint64, error) {
+	b.lock.RLock()
+	defer b.lock.RUnlock()
+	var sum uint64
+	for i := range idxs {
+		if b.validatorsMultiValue == nil {
+			return 0, errors.Wrap(state.ErrNilValidatorsInState, "nil validators multi-value slice")
+		}
+		v, err := b.validatorsMultiValue.At(b, uint64(idxs[i]))
+		if err != nil {
+			return 0, errors.Wrap(err, "validators multi value at index")
+		}
+		sum += v.EffectiveBalance
+	}
+	return sum, nil
+}
+
 func (b *BeaconState) validatorAtIndex(idx primitives.ValidatorIndex) (*ethpb.Validator, error) {
 	if b.validatorsMultiValue == nil {
 		return &ethpb.Validator{}, nil

beacon-chain/state/stategen/mock/mock.go

@@ -5,6 +5,7 @@ import (
 	"context"
 
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/state"
+	"github.com/OffchainLabs/prysm/v7/beacon-chain/state/stategen"
 	"github.com/OffchainLabs/prysm/v7/consensus-types/primitives"
 )
 
@@ -14,6 +15,8 @@ type StateManager struct {
 	StatesBySlot map[primitives.Slot]state.BeaconState
 }
 
+var _ stategen.StateManager = (*StateManager)(nil)
+
 // NewService --
 func NewService() *StateManager {
 	return &StateManager{
@@ -101,3 +104,8 @@ func (m *StateManager) AddStateForSlot(state state.BeaconState, slot primitives.
 func (m *StateManager) DeleteStateFromCaches(context.Context, [32]byte) error {
 	return nil
 }
+
+// FinalizedReadOnlyBalances --
+func (m *StateManager) FinalizedReadOnlyBalances() stategen.NilCheckableReadOnlyBalances {
+	panic("unimplemented")
+}

beacon-chain/state/stategen/service.go

@@ -27,6 +27,13 @@ var defaultHotStateDBInterval primitives.Slot = 128
 
 var populatePubkeyCacheOnce sync.Once
 
+// NilCheckableReadOnlyBalances adds the IsNil method to ReadOnlyBalances
+// to allow checking if the underlying state value is nil.
+type NilCheckableReadOnlyBalances interface {
+	state.ReadOnlyBalances
+	IsNil() bool
+}
+
 // StateManager represents a management object that handles the internal
 // logic of maintaining both hot and cold states in DB.
 type StateManager interface {
@@ -43,6 +50,7 @@ type StateManager interface {
 	ActiveNonSlashedBalancesByRoot(context.Context, [32]byte) ([]uint64, error)
 	StateByRootIfCachedNoCopy(blockRoot [32]byte) state.BeaconState
 	StateByRootInitialSync(ctx context.Context, blockRoot [32]byte) (state.BeaconState, error)
+	FinalizedReadOnlyBalances() NilCheckableReadOnlyBalances
 }
 
 // State is a concrete implementation of StateManager.
@@ -201,3 +209,8 @@ func (s *State) FinalizedState() state.BeaconState {
 	defer s.finalizedInfo.lock.RUnlock()
 	return s.finalizedInfo.state.Copy()
 }
+
+// Returns the finalized state as a ReadOnlyBalances so that it can be used read-only without copying.
+func (s *State) FinalizedReadOnlyBalances() NilCheckableReadOnlyBalances {
+	return s.finalizedInfo.state
+}

beacon-chain/sync/custody.go

@@ -185,7 +185,7 @@ func (s *Service) validatorsCustodyRequirement() (uint64, error) {
 	}
 
 	// Retrieve the finalized state.
-	finalizedState := s.cfg.stateGen.FinalizedState()
+	finalizedState := s.cfg.stateGen.FinalizedReadOnlyBalances()
 	if finalizedState == nil || finalizedState.IsNil() {
 		return 0, nilFinalizedStateError
 	}

changelog/kasey_copy-free-balance-lookup.md

@@ -0,0 +1,2 @@
+### Fixed
+- Avoid copying the full finalized state every time we compute cgc.

changelog/tt_apply_execution_payload.md

@@ -0,0 +1,2 @@
+### Ignored
+- Refactor ProcessExecutionPayload to ApplyExecutionPayload